1. Field of the Invention
The present invention relates to an organic electroluminescence (EL) display unit that emits light using organic EL phenomenon, and a method of manufacturing the organic EL display unit.
2. Description of the Related Art
As development of the information communication industry accelerates, there is a demand for display devices having advanced performance. Organic EL devices that are receiving attention as next-generation display devices have the advantage of not only having a wide viewing angle and superior contrast as a spontaneous-emission display device, but also having a fast response time.
A light emitting layer and the like composing the organic EL device are largely classified into low molecular materials and polymer materials. The low molecular materials are generally known to indicate higher emission efficiency and longer life, and are also considered to have, in particular, high blue-color capability.
In addition, as a method for forming an organic layer of the organic EL device, a low-molecular material is formed by a dry process (evaporation method) such as a vacuum evaporation method, and the polymer material is formed by a wet process (coating method), such as a spin coat method, an inkjet method, a nozzle coat method.
The vacuum evaporation method has the advantages of not needing to dissolve the formation material of the organic thin film in a solvent, and not needing a procedure for removing the solvent after film formation. However, the vacuum evaporation method has disadvantages, such as separate coatings by metal masking being difficult, application onto a large screen substrate being difficult since equipment manufacturing costs for manufacturing a large-scale panel in particular are high, and mass production also being difficult. Therefore, the inkjet method and the nozzle coat method in which enlarging the area of the display screen is comparatively easy are receiving attention.
However, among the polymer materials used in the inkjet method and the nozzle coat method, blue light emitting materials in particular have low emission efficiency and life characteristics, and are not practical. Therefore, patterning by the wet process has been considered difficult.
For example, in Japanese Unexamined Patent Application Publication No. 2006-140434, a display unit is disclosed in which a blue light emitting layer and subsequent layers as common layers are formed by the vacuum evaporation method in the upper sections of a red light emitting layer and a green light emitting layer formed by the wet process including the inkjet method. As a result of such a structure, micro-patterning of the blue light emitting layer becomes unnecessary, and the possibility of size increase becomes high.